CN107106848A - Pattern switching is carried out by ventricular leadless pacing devices - Google Patents

Abstract

In some examples, a leadless pacing device (hereinafter "LPD") is configured for implantation in a ventricle of a patient's heart and is configured for Switching between an atrioventricular synchronous pacing mode and an asynchronous ventricular pacing mode, the sensed event may be an undersensing event, for example. In some examples, the LPD is configured to switch from the no-pacing sensing mode in response to determining for a threshold number of cardiac cycles that no ventricular depolarization is detected within a ventricular event detection window beginning at an atrial activation event to atrioventricular synchronized pacing mode.

Description

Mode Switching by Ventricular Leadless Pacing Devices

technical field

The present disclosure relates to cardiac pacing, and more particularly to cardiac pacing using leadless pacing devices.

Background technique

Implantable pacemakers can deliver pacing pulses to a patient's heart and monitor the condition of the patient's heart. In some examples, the implantable pacemaker includes a pulse generator and one or more electrical leads. The pulse generator may, for example, be implanted in a small pocket in the patient's chest. The electrical leads may be coupled to a pulse generator, which may contain circuitry to generate pacing pulses and/or sense electrical activity of the heart. The electrical leads may extend from the pulse generator to a target site (eg, atria and/or ventricles) such that electrodes at the distal ends of the electrical leads are positioned at the target site. The pulse generator may provide electrical stimulation to the target site and/or monitor electrical activity of the heart at the target site via electrodes.

A leadless pacing device for sensing electrical activity and/or delivering therapeutic electrical signals to the heart has also been proposed. The leadless pacing device may include one or more electrodes on its housing for delivering therapeutic electrical signals and/or sensing intrinsic depolarization of the heart. The leadless pacing device may be positioned inside or outside the heart, and in some examples may be anchored to the wall of the heart via a fixation mechanism.

Contents of the invention

The present disclosure describes a leadless pacing device (hereinafter "LPD") configured for implantation in a ventricle of a patient's heart, and configured for detecting Switching from no-paced sensing mode to atrioventricular-synchronized pacing mode upon one or more ventricular undersensing events. In some examples, the LPD is further configured to switch between an atrioventricular synchronous pacing mode and an asynchronous ventricular pacing mode in response to detecting one or more atrial undersensing events. In the atrioventricular synchronized pacing mode, the LPD times the delivery of pacing pulses to the ventricles of the patient's heart relative to atrial activation events that may be events that result in atrial contraction. In the asynchronous ventricular pacing mode, the LPD is configured to: Intrinsic ventricular depolarization, a ventricular pacing pulse is delivered.

In some examples, while the LPD is in an atrioventricular synchronized pacing mode, a processing module of a therapy system including the LPD may determine whether an atrial activation event detection window begins at a ventricular activation event, e.g., based on electrical cardiac signals Atrial activating events of the heart are detected. In response to determining that the atrial activating event is detected within the atrial activating event detection window, and in response to further determining that after the detected atrial activating event (e.g., within the atrioventricular (AV) ) interval) no ventricular activation event is detected, and the processing module may control the LPD to deliver ventricular pacing pulses according to the atrioventricular synchronous pacing mode. However, if the processing module detects no atrial activating event within the atrial activating event detection window and determines that no atrial activating event is detected within the atrial activating event detection window of a threshold number of cardiac cycles, the processing module may An undersensing event was detected. In response to detecting the undersensing event, the processing module may control the LPD to switch from the atrioventricular synchronous pacing mode to an asynchronous ventricular pacing mode.

In one aspect, the present disclosure relates to a method comprising: receiving, by a processing module, electrical signals of a patient sensed by a leadless pacing device while the leadless pacing device is in a no-pace sensing mode. a cardiac signal; detecting, by the processing module and based on the electrical cardiac signal, an atrial activation event; determining, by the processing module and based on the electrical cardiac signal, that no ventricular event detection window begins at the atrial activation event detecting a ventricular sensing event; and controlling, by the processing module, the leadless pacing device from the no-pacing sensing mode based on a determination that the ventricular sensing event was not detected within the ventricular event detection window Switching to the atrioventricular synchronous pacing mode, wherein the operation of controlling the leadless pacing device to switch to the atrioventricular synchronous pacing mode includes controlling the leadless pacing device to switch to the atrioventricular synchronous pacing mode according to the atrioventricular synchronous pacing mode The patient delivers pacing pulses.

In another aspect, the present disclosure relates to a leadless pacing system comprising: a leadless pacing device configured to sense electrical cardiac signals and configured to configured to operate in a no-pace sensing mode and an atrioventricular pacing mode; and a processing module configured to receive data from a leadless pacing device when the leadless pacing device is in a no-pace mode. an electrical cardiac signal sensed while in the beat sensing mode, an atrial activation event is detected based on the electrical cardiac signal, an atrial activation event is determined to be detected within a ventricular event detection window starting at the atrial activation event based on the electrical cardiac signal to a ventricular sensing event, and controlling the leadless pacing device to switch from the no-pacing sensing mode to atrioventricular synchronization based on determining that the ventricular sensing event is not detected within the ventricular event detection window pacing mode, wherein the processing module is configured to control the leadless pacing device at least by controlling the leadless pacing device to deliver pacing pulses to the patient according to the atrioventricular synchronized pacing mode Switch to the AV synchronized pacing mode.

In another aspect, the present disclosure relates to a system comprising: for detecting atrial means for an activating event; means for determining, based on the electrical cardiac signal, that a ventricular sensing event has not been detected within a ventricular event detection window beginning at the atrial activating event; The pacing device is controlled to deliver pacing pulses to the patient according to the atrioventricular synchronized pacing mode based on determining that the ventricular sensed event is not detected within the ventricular event detection window. A device for switching from the non-pacing sensing mode to the atrioventricular synchronous pacing mode.

In another aspect, the present disclosure relates to a computer-readable storage medium comprising instructions that, when executed by a processing module, cause the processing module to: detecting an atrial activation event from an electrical cardiac signal sensed while the pacing device is in a no-pacing sensing mode; determining, based on the electrical cardiac signal, that no ventricles were detected within a ventricular event detection window beginning at the atrial activation event sensing an event; and controlling the leadless pacing device to switch from the no-pacing sensing mode to an atrioventricular synchronized pacing mode based on determining that the ventricular sensing event is not detected within the ventricular event detection window , wherein the operation of controlling the leadless pacing device to switch to the atrioventricular synchronous pacing mode includes controlling the leadless pacing device to deliver pacing pulses to the patient according to the atrioventricular synchronous pacing mode.

In another aspect, the present disclosure relates to a method comprising: receiving, by a processing module, an electrical cardiac signal sensed by a leadless pacing device while the leadless pacing device is in an atrioventricular synchronized pacing mode. signal; detecting, by the processing module, a first atrial activating event; determining, by the processing module and based on the electrical cardiac signal, that a second atrial activating event was not detected within a detection window beginning at the first atrial activating event; and by The processing module controls the leadless pacing device to deliver pacing pulses to a ventricle of the patient according to an asynchronous ventricular pacing mode based on determining that the second atrial activation event is not detected within the detection window.

In another aspect, the present disclosure relates to a leadless pacing system comprising:

a leadless pacing device configured to sense electrical cardiac signals and to deliver pacing therapy to the patient's heart; and a processing module configured to use determining a start at the first atrial activation event based on the electrical cardiac signal and upon detecting a first atrial activation event based on the electrical cardiac signal and while the leadless pacing device is in an atrioventricular synchronized pacing mode A second atrial activating event is not detected within the detection window, and based on determining that the second atrial activating event is not detected within the detection window, controlling the delivery of the leadless pacing device to the patient according to an asynchronous ventricular pacing mode The ventricles deliver pacing pulses.

In another aspect, the present disclosure relates to a system comprising: a system for determining a cardiac signal based on an electrical cardiac signal sensed by a leadless pacing device while the leadless pacing device is in an atrioventricular synchronized pacing mode. means for detecting a first atrial activating event; means for determining, based on the electrical cardiac signal, that a second atrial activating event has not been detected within a detection window beginning at the first atrial activating event; and means for controlling the Means for the leadless pacing device to deliver pacing pulses to a ventricle of a patient according to an asynchronous ventricular pacing mode based on determining that the second atrial activation event is not detected within the detection window.

In another aspect, the present disclosure relates to a computer-readable storage medium comprising instructions that, when executed by a processing module, cause the processing module to: detecting a first atrial activation event based on an electrical cardiac signal sensed while the pacing device is in an atrioventricular synchronized pacing mode; and determining, based on the electrical cardiac signal, that no to a second atrial activating event; and controlling the leadless pacing device to deliver pacing pulses to a ventricle of the patient according to an asynchronous ventricular pacing mode based on determining that the second atrial activating event is not detected within the detection window.

In another aspect, the present disclosure relates to a computer-readable storage medium including computer-readable instructions executable by a processor. The instructions cause a programmable processor to perform all or part of any of the techniques described herein. The instructions may be, for example, software instructions, such as those defining a software or computer program. The computer-readable medium can be a computer-readable storage medium, such as a storage device (e.g., a magnetic disk drive, or an optical drive), a memory (e.g., flash memory, read-only memory (ROM), or random-access memory (RAM)), or a storage Any other type of volatile or nonvolatile memory with instructions (eg, in a computer program or other executable form) to cause a programmable processor to perform the techniques described herein. In some examples, the computer readable medium is a work of manufacture and is non-transitory.

The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

Description of drawings

1 is a conceptual diagram illustrating an example leadless pacing device configured to deliver atrioventricular synchronous pacing and asynchronous ventricular pacing.

FIG. 2 is a conceptual diagram illustrating a leadless pacing system including the example leadless pacing device of FIG. 1 .

3A is a conceptual diagram illustrating another exemplary leadless pacing system including a leadless pacing device configured to deliver atrioventricular synchronous pacing and asynchronous ventricular pacing.

3B is a conceptual diagram illustrating the leadless pacing device of FIG. 3A.

4 is a functional block diagram illustrating an example configuration of the example leadless pacing device of FIG. 1 .

Figure 5 is a timing diagram illustrating normal conduction timing in a patient.

6A is a timing diagram illustrating an exemplary technique for controlling a leadless pacing device to switch from a no-pace sensing mode to an atrioventricular synchronized pacing mode.

6B is a timing diagram illustrating another exemplary technique for controlling a leadless pacing device to switch from a no-pace sensing mode to an atrioventricular synchronized pacing mode.

7 is a flowchart of an exemplary technique for controlling switching of a leadless pacing device implanted in a ventricle of a heart from a no-pace sensing mode to an atrioventricular synchronized pacing mode.

8 is a flowchart of an exemplary technique for delivering pacing pulses to the ventricles of a heart according to an atrioventricular synchronized pacing mode.

9 is a timing diagram illustrating an example of asynchronous ventricular pacing.

10 is a flowchart of an exemplary technique for delivering pacing pulses to the ventricles of a heart according to an asynchronous ventricular pacing mode.

11 is a flowchart of an exemplary technique for controlling a leadless pacing device implanted in a ventricle of a heart to switch from an atrioventricular synchronous pacing mode to an asynchronous ventricular pacing mode.

FIG. 12 is a timing diagram illustrating an example application of the technique of FIG. 11 .

detailed description

In some instances, a dual chamber implantable pacemaker is implanted in a pocket in the patient's chest and coupled to a right atrial lead and a right ventricular lead. The right atrial lead extends from the implantable pacemaker in the bag to the right atrium of the patient's heart and positions one or more electrodes within the right atrium. The right ventricle lead extends from the implantable pacemaker in the bag to the right ventricle of the patient's heart and positions one or more electrodes within the right ventricle.

Such a dual chamber implantable pacemaker senses corresponding cardiac electrical activity, such as a corresponding cardiac electrogram, via one or more electrodes implanted in the right atrium or one or more electrodes implanted in the right ventricle. Specifically, this dual chamber implantable pacemaker detects intrinsic atrial depolarization via one or more electrodes implanted in the right atrium and intrinsic ventricular depolarization via one or more electrodes implanted in the right ventricle change. The implantable pacemaker can also deliver pacing pulses to the right atrium and right ventricle through one or more electrodes in the right atrium and right ventricle, respectively.

Due to the ability to sense both atrial and ventricular electrical activity, such dual chamber implantable pacemakers may be able to provide atrioventricular synchronized pacing. For patients with intermittent AV nodal conduction, it may be more preferable to inhibit ventricular pacing and allow intrinsic ventricular depolarization to occur at a time (termed the AV interval) following intrinsic atrial depolarization or atrial pacing. This type of AV-synchronized pacing of a dual-chamber implantable pacemaker is known as the VDD programming mode and can be used in patients with various degrees of AV block.

Alternatively, a dual-chamber implantable pacemaker can provide asynchronous ventricular pacing. Asynchronous ventricular pacing may be preferred if the patient's heart rate becomes irregular. According to the asynchronous ventricular pacing mode, if no intrinsic ventricular depolarization is detected within the "VV interval" from when the previous intrinsic depolarization was detected or when the previous intrinsic ventricular pacing pulse was delivered, the dual chamber implantable A pacemaker delivers ventricular pacing pulses. If the VV interval is rate adaptive (i.e., the implantable pacemaker can sense changes in the patient's heart rate and change the VV interval accordingly), then performed by a dual chamber implantable cardiac pacemaker Such asynchronous ventricular pacing is called VVI programming mode or VVIR programming mode.

Implantable cardiac leads and the bag into which the pacemaker is implanted may be linked to complications. To avoid such complications, leadless pacing devices sized to be implanted fully within the heart (eg, in one chamber of the heart such as the right ventricle) have been proposed. Some proposed leadless pacing devices include a plurality of electrodes attached to or part of the housing of a corresponding leadless pacing device ("LPD").

In some examples, the LPDs described herein are configured for pacing in an atrial-synchronous-ventricular mode and an asynchronous-ventricular mode. As discussed below, the processing module may select a mode in which the LPD delivers pacing pulses to the patient's heart based on detection of an atrial undersensing event.

Due to the placement of the LPD in the ventricle, the electrical activity of the right atrium sensed by the electrodes of the LPD implanted in the ventricle may be of relatively low power (e.g., low-amplitude P waves), which may cause the LPD to be based on the The electrical cardiac signal did not sense atrial activation events. This can lead to atrial undersensing events.

In some examples, the processing module controls the LPD to switch from the atrial synchronous ventricular pacing mode to the asynchronous ventricular pacing mode in response to detecting an atrial undersensing event. When switching from the atrioventricular synchronous pacing mode to the asynchronous ventricular pacing mode, the LPD terminates delivery of pacing pulses in accordance with the atrioventricular synchronous mode and sends a pacing pulse in accordance with the asynchronous ventricular pacing mode to The patient delivers pacing pulses.

The processing module may attempt to detect an atrial activating event (eg, an event resulting in atrial contraction) within an atrial activating event detection window beginning at a ventricular activating event (eg, an intrinsic ventricular depolarization or delivery of a pacing pulse to the ventricle). In some examples, the atrial activation event is detection of a far-field P-wave in the electrical cardiac signal sensed by an LPD implanted in the ventricle, detection of another device (e.g., another LPD implanted in the atrium) Atrial pacing pulses are delivered or mechanical contractions of the atria are detected.

In response to determining that an atrial activating event is detected within the atrial activating event detection window, the processing module may control the LPD to deliver ventricular pacing pulses based on timing of the atrioventricular synchronized pacing mode. For example, in response to further determining that no ventricular activating event is detected after the detected atrial activating event (e.g., within the AV interval), the processing module may control the LPD to follow the detected atrial activating event at a predetermined Time intervals to deliver ventricular pacing pulses.

However, in response to determining that an atrial activating event is not detected within the atrial activating event detection window, the processing module may increment an undersensing event counter or generate an undersensing indication, which may be determined by the Flags, values or other parameters stored in the memory of the LPD or other device. In some examples, the processing module may deliver ventricular pacing pulses (e.g., a VV interval plus a bias) during a time period following a previous ventricular activation event, where the VV interval may be based on historical VV interval data or pre-programmed VV interval).

In response to determining that the counter value is greater than or equal to an undersensing event threshold or after the processing module generates a certain number of undersensing indications (e.g., within a specified time period), the processing module may control the LPD Switch from synchronous ventricular pacing mode to asynchronous ventricular pacing mode. The processing module may determine that an undersensing event has occurred in response to determining that the counter value is greater than or equal to a predetermined undersensing event threshold or in response to determining that the number of undersensing indications is greater than or equal to a predetermined undersensing event threshold . The predetermined undersensing event threshold may be, for example, one, while in other examples, the predetermined threshold may be more than one, such as two, three or more than four.

In some examples, the counter may count the number of consecutive cardiac cycles that generate the indication of sensory insufficiency. In other examples, the counter may count the number of cardiac cycles ("X") out of a predetermined number of consecutive cardiac cycles ("Y") that generate the undersensing indication. This may be referred to as an "X of Y" counter. In other examples, the counter may count the number of cardiac cycles within a predetermined time period within which the undersensing indication is generated.

In examples where the predetermined threshold is more than one, the LPD may not switch to the asynchronous ventricular pacing mode immediately after detecting one instance of atrial undersensing. This may allow the patient's heart to restore intrinsic conduction. In this manner, the LPD may be configured to determine whether the heart has restored intrinsic conduction prior to switching to the asynchronous ventricular pacing mode. In some cases, the atrioventricular synchronized pacing mode can promote better synchronization of the patient's heart. In at least some of these cases, the LPD may be configured to help promote better synchronization of the heart.

In some examples, the LPD is configured to operate in a no-pace sensing mode (eg, a mode corresponding to the ODO mode of a dual-chamber pacemaker with leads). For example, the LPD may operate in a non-paced sensing mode as an initial mode upon implantation of the LPD in the ventricle prior to delivering any pacing therapy to the patient. In the no-pace sensing mode, the LPD senses electrical activity of the heart, but does not deliver any pacing therapy to the patient's heart.

In some examples described herein, the LPD is configured to switch from a no-pace sensing mode to atrioventricular synchronization in response to detecting insufficient ventricular sensing while the LPD is in the no-pace sensing mode. beat mode. When the LPD switches to the atrioventricular synchronized pacing mode, the LPD begins delivering pacing stimuli to the patient.

When the LPD does not detect (e.g., sense) a cardiac sensing event for a predetermined number of cardiac cycles within a ventricular event detection window V _ACT beginning at an atrial activation event (either an intrinsic event or a delivered atrial pacing pulse) , ventricular undersensing may have occurred. A ventricular sensing event may also be referred to as a ventricular depolarization event. Each occurrence of a ventricular undersensing event may indicate that the ventricles will not conduct intrinsically within the expected time after the atrial activation event. Ventricles may not conduct intrinsically, for example due to atrioventricular (AV) block. Thus, ventricular undersensing may occur due to AV block.

In instances where the predetermined threshold number of ventricular events is more than one, the ventricles of the patient's heart may not depolarize or contract properly during the cardiac cycle in which the ventricular event occurred. As a result, the patient's heart may miss a beat. This may be referred to as a "missing" heartbeat caused by the LPD. By being configured to miss one or more heartbeats, the LPD may be configured to sense intrinsic Conduction provides time to favor the intrinsic conduction of the heart, wherein the LPD delivers a ventricular pacing pulse that may take precedence over the intrinsic conduction of the heart. In this manner, the LPD can sense intrinsic activity of the heart for at least one complete heartbeat prior to delivering ventricular pacing pulses in the atrioventricular synchronized pacing mode.

The predetermined threshold number of ventricular events affects the number of heartbeats that may be missed before the LPD switches to an atrioventricular synchronized pacing mode. For example, if the predetermined threshold number of ventricular events is one, the heart may miss a beat before the LPD switches to an atrioventricular synchronized pacing mode. As another example, if the undersensing threshold is two, the heart may miss two beats before switching to AV synchronized pacing mode.

1 is a conceptual diagram illustrating an exemplary leadless pacing device (LPD) 10A configured to operate in a paceless sensing mode and deliver atrioventricular synchronous pacing and asynchronous ventricular pacing. In some examples, whether LPD 10A operates in a no-paced sensing mode or in an atrioventricular-synchronized pacing mode is controlled based on the detection of insufficient ventricular sensing, as described below with respect to FIGS. 6A , 6B, and 7 . described in further detail. Whether LPD 10A delivers pacing pulses to the patient in the AV-synchronous pacing mode or in the asynchronous ventricular pacing mode is controlled based on the detection of an atrial undersensing event, as described in further detail below.

As shown in FIG. 1 , LPD 10A includes housing 12 , fixed teeth 14A- 14D (collectively "fixed teeth 14 "), and electrodes 16A and 16B. Housing 12 is configured such that, for example, it has a size and form factor that allows LPD 10A to be fully implanted within a chamber of the heart, such as the right ventricle. As illustrated in FIG. 1 , in some examples, housing 12 may have a cylindrical (eg, pill-shaped) form factor. The housing 12 may be hermetically sealed to prevent liquids from entering the interior of the housing 12 .

Fixed teeth 14 extend from housing 12 and are configured to engage heart tissue to substantially fix the position of housing 12 within a chamber of the heart, such as at or near the apex of the right ventricle. Fixation teeth 14 are configured to anchor housing 12 to cardiac tissue such that LPD 10A moves with the cardiac tissue during systole. The fixed teeth 14 may be fabricated from any suitable material, such as a shape memory material (eg, Nitinol). The number and configuration of fixation teeth 14 shown in FIG. 1 is only one example, and other numbers and configurations of fixation teeth for anchoring the LPD housing to cardiac tissue are contemplated. Additionally, while LPD 10A includes a plurality of fixation teeth 14 configured to anchor LPD 10A to cardiac tissue in a heart chamber, in other examples, LPD 10A may use other types of fixation mechanisms such as, but not limited to barbs, coils, etc.) to cardiac tissue.

LPD 10A is configured to sense the electrical activity of the heart (ie, electrocardiogram (“EGM”)) and deliver pacing pulses to the right ventricle via electrodes 16A and 16B. Electrodes 16A and 16B may be mechanically connected to housing 12 or may be defined by conductive portions of housing 12 . In either case, electrodes 16A and 16B are electrically isolated from each other. Electrode 16A may be referred to as a tip electrode, and fixed teeth 14 may be configured to anchor LPD 10A to cardiac tissue such that electrode 16A remains in contact with the cardiac tissue. Electrode 16B may be defined by a conductive portion of housing 12 and, in some examples, may define at least a portion of a power supply housing that houses a power source (eg, a battery) for LPD 10A. In some examples, a portion of housing 12 may be covered or formed of an insulating material to isolate electrodes 16A and 16B from each other and/or to provide a desired size and shape for one or both electrodes 16A and 16B.

Housing 12 houses the electronic components of LPD 10A, such as an electrical sensing module, sensors for sensing electrical activity of the heart via electrodes 16A and 16B, and an electrical stimulation module for delivering pacing pulses through electrodes 16A and 16B. Electronic components may include any discrete and/or integrated electronic circuit components that implement analog and/or digital circuits capable of producing the functions attributed to the LPD described herein. Additionally, housing 12 may house memory that includes instructions that, when executed by one or more processors housed in housing 12 , cause LPD 10A to perform various functions pertaining to LPD 10A herein. In some examples, housing 12 may house a communication module that enables LPD 10A to communicate with other electronic devices, such as a medical device programmer. In some examples, housing 12 may house an antenna for wireless communication. Housing 12 may also house a power source, such as a battery. The electronic components of LPD 10A will be described in further detail below with respect to FIG. 4 .

FIG. 2 is a conceptual diagram illustrating an example leadless pacing system 20A including the example LPD 10A of FIG. 1 . In the example of FIG. 2 , LPD 10A is implanted in right ventricle 22 of heart 24 of patient 26 . More specifically, LPD 10A is fixed or attached via fixed teeth 14 to the inner wall of right ventricle 22 , in the example of FIG. 2 near the apex of the right ventricle. In other examples, LPD 10A may be affixed to the inner wall of right ventricle 22 at another location, such as on the intraventricular septum or free wall of right ventricle 22, or may be affixed to the exterior of heart 24, for example, epicardially proximal to the right ventricle. twenty two. In other examples, LPD 10A may be secured within, on, or near the left ventricle of heart 24 .

LPD 10A includes a plurality of electrodes attached to or part of the housing of LPD 10A (ie, electrodes 16A and 16B). LPD 10A may be configured for sensing electrical cardiac signals (eg, EGM) associated with depolarization and repolarization of heart 24 via electrodes 16A and 16B. LPD 10A is also configured to deliver cardiac pacing pulses to right ventricle 22 via electrodes 16A and 16B. In some examples, LPD 10A may deliver cardiac pacing pulses according to an atrioventricular synchronous pacing mode or an asynchronous ventricular pacing mode, depending on whether one or more undersensing events are detected.

LPD 10A is configured to detect ventricular activation events in any suitable manner. In some examples, the processing module of LPD 10A is configured to detect ventricular activation events based on ventricular electrical activity (eg, R-waves), which may be indicative of intrinsic depolarization of right ventricle 22 . The processing module is configured to detect a ventricular activation event based on the delivery of pacing pulses to the right ventricle 22 in addition to or instead of the ventricular electrical activity. In yet other examples, the processing module may be configured to detect a ventricular activation event based on detection of ventricular contraction, which may be based on a heart sound (e.g., S1 heart sound) sensed by a sensor of the LPD 10A or based on movement of the right ventricle. The ventricular contraction is detected (eg, sensed by a motion sensor of the LPD 10A or another device).

LPD 10A is configured to detect atrial activation events in any suitable manner. In some examples, LPD 10A is configured to detect atrial activation events based on mechanical contraction of right atrium 28, based on detection of atrial depolarization within the electrical cardiac signal, or based on both mechanical contraction and atrial depolarization. LPD 10A may detect atrial depolarization, for example, by detecting at least a P-wave representative of atrial depolarization within an electrocardiographic signal.

In some examples, LPD 10A may sometimes sense insufficient atrial activation events. For example, LPD 10A may not be able to reliably detect atrial depolarization, for example, due to the quality of the electrical signal sensed by electrodes 16A, 16B of LPD 10A or a relatively small magnitude of atrial depolarization within the sensed electrical cardiac signal. Cause of polarization (eg, small P wave amplitude). As described in more detail below, in some examples, LPD 10A is configured to switch from an atrioventricular synchronous pacing mode to an asynchronous pacing mode in response to detection of an atrial undersensing event.

In contrast to LPD 10A (a dual chamber cardiac pacemaker that is electrically connected to leads extending to the right ventricle 22 and right atrium 28 of the heart 24), the LPD 10A (and other LPDs) can utilize electrodes placed in the right atrium 28 to sense atrial activity. As a result, the P-wave of the electrical cardiac signal sensed by a dual chamber pacemaker (or other pacemaker with a lead in the right atrium 28) may have a greater amplitude than the P-wave of the electrical cardiac signal sensed by the LPD 10A amplitude. Electrical cardiac signals with larger P-wave amplitudes may result in fewer atrial undersensing events. Therefore, switching from an atrioventricular synchronous pacing mode to an asynchronous pacing mode in response to detection of an atrial undersensing event, as described herein with respect to LPD, may not be applicable to dual chamber pacemakers (or those with leads) or provide improved utility for dual-chamber pacemakers.

As shown in FIG. 2 , LPD system 20A also includes a medical device programmer 18 configured to program and retrieve data from LPD 10A. Programmer 18 may be a handheld computing device, desktop computing device, networked computing device, or the like. Programmer 18 may include a computer-readable storage medium having instructions that cause the processing modules of programmer 18 to provide the functionality attributed to programmer 18 in the present disclosure. LPD 10A can communicate with programmer 18 wirelessly. For example, LPD 10A may transmit data to and receive data from programmer 18 . Programmer 18 may also program and/or wirelessly charge LPD 10A wirelessly.

Data retrieved from LPD 10A using programmer 18 may include electrical cardiac signals stored by LPD 10A indicative of electrical activity of heart 24, generated sensing deficit indications, and indicative of sensing, diagnostic, and therapeutic events associated with LPD 10A. Marker channel data for the occurrence and timing of (eg, detection of atrial and ventricular depolarization and delivery of pacing pulses). Data transferred to LPD 10A using programmer 18 may include, for example, an operating program for LPD 10A that causes LPD 10A to function as described herein. As an example, data transferred to LPD 10A using programmer 18 may include the length of any AV interval, the length of any VV interval, atrial systole detection delay, ventricular activation event detection window, atrial activation event detection window, and parameters for determining Improved deviation of the atrial activation event detection window, these are described in further detail below. Any thresholds may also be included, such as for detecting atrial and/or ventricular contraction, for detecting an undersensing event (e.g., based on some undersensing indication), or programmed for use by the LPD 10A, based on heart 24, patient 26, or LPD 10A parameters to determine such values.

FIG. 3A is a conceptual diagram illustrating another example leadless pacing system 20B that includes a pacing system configured for pacing in a no-pacing mode and in a ventricle in some examples. Another exemplary LPD 10B operating in mode. Additionally or conversely, or in some examples, like LPD 10A, LPD 10B is configured to deliver atrioventricular synchronous pacing or asynchronous ventricular pacing based on the detection of one or more undersensing events. either one. Figure 3B shows the LPD 10B in more detail. Leadless pacing system 20B and LPD 10B may be substantially the same as leadless pacing system 20A and LPD 10A described above with reference to FIGS. 1 and 2 . However, unlike LPD 10A, LPD 10B is coupled to sensing extension 30 , which includes electrode 32 . In some examples, sensing extension 30 may include one or more additional electrodes having the same polarity as electrode 32 . Although not shown in FIGS. 3A and 3B , LPD 10B may include electrode 16A, but may not include electrode 16B, as described above with reference to LPD 10A and FIG. 1 .

Electrodes 32 are connected through electrical conductors 34 of sensing extension 30 to the electronics (eg, electrical sensing module and stimulation module) within the housing of LPD 10B. In some examples, electrical conductor 34 is connected to the electronics through a conductive portion 36A of housing 36 of LPD 12B, which may correspond to electrode 16B of LPD 10A ( FIG. 1 ) but may be substantially completely insulated (eg, , completely insulated or almost completely insulated). Substantially completely insulating conductive portion 36A of housing 36 may allow electrical sensing module of LPD 10B to sense cardiac electrical activity with electrodes 32 of sensing extension 30 instead of conductive portion 36A of housing 36 . This may help to improve the magnitude of atrial depolarization present in the electrical cardiac signal sensed via the LPD 10B, particularly with respect to electrodes 16A, 16B being fixed to or as part of the housing of the LPD 10A. example (Figure 1).

Additionally, as shown in FIGS. 3A and 3B , sensing extension 30 extends away from LPD 10B, which enables electrode 32 to be positioned relatively close to right atrium 28 . As a result, the electrical cardiac signal sensed by LPD 10B via electrode 16A (FIG. 1) and electrode 32 may comprise a higher amplitude than the electrical cardiac signal sensed by LPD 10A via electrodes 16A and 16B (FIG. Far-field atrial depolarization signal. In this manner, sensing extension 30 may facilitate detection of atrial depolarization when LPD 10B is implanted within right ventricle 22 . In some examples, sensing extension 30 is sized to be fully implanted within right ventricle 22 . In other examples, sensing extension 30 is sized to extend into right atrium 28 .

While sensing extension 30 , LPD 10B may occasionally be able to detect depolarization of right atrium 28 , for example, due to reduced electrical cardiac signal quality. Reduced electrical cardiac signal quality may include reduced amplitude and/or increased noise of the atrial component of the electrical cardiac signal, which may result in undersensing of atrial events by LPD 10B when LPD 10B is implanted in right ventricle 22 . Degradation of electrical cardiac signal quality may result, for example, from movement of sensing extension 30 relative to right atrium 28, which may be caused by posture or activity of patient 26, or other conditions of patient 26, heart 24, and/or LPD 10B . To help provide responsive pacing therapy, LPD 10B may be configured to deliver pacing pulses to right ventricle 22 according to either an atrioventricular synchronous pacing mode or an asynchronous ventricular pacing mode upon detection of an atrial undersensing event.

While the remainder of this disclosure refers primarily to LPD 10A, the description of LPD 10A also applies to LPD 10B and other LPDs configured to provide both atrial-synchronous and asynchronous ventricular pacing.

4 is a functional block diagram illustrating an example configuration of an LPD 10A configured to deliver atrioventricular synchronous pacing or asynchronous ventricular pacing based on the detection of an atrial sensing event. The LPD 10B of FIGS. 3A and 3B may have a configuration similar to that of the LPD 10A. However, electrode 16B of LPD 10A may be replaced by electrode 32 of LPD 10B, which may be positioned at a greater distance from electrode 16A and LPD 10B, as described above with reference to FIGS. 3A and 3B .

LPD 10A includes a processing module 40 , memory 42 , stimulation module 44 , electrical sensing module 46 , sensors 48 , communication module 50 and power supply 52 . Power source 52 may include batteries, such as rechargeable or non-rechargeable batteries.

The modules included in the LPD 10A represent functions that may be included in the LPD 10A of the present disclosure. The modules of the present disclosure may comprise any discrete and/or integrated electronic circuit components implementing analog and/or digital circuits capable of producing the functions ascribed to the modules herein. For example, the modules may include analog circuits such as amplification circuits, filter circuits, and/or other signal conditioning circuits. The modules may also include digital circuits, eg, combinational or sequential logic circuits, memory devices, and the like. The functions attributed to the modules herein may be embodied as one or more processors, hardware, firmware, software, or any combination thereof. Depiction of different features as modules is intended to highlight different functional aspects and does not necessarily imply that such modules must be realized by separate hardware or software components. Rather, functions associated with one or more modules may be performed by separate hardware or software components, or integrated within common or separate hardware or software components.

The processing module 40 may comprise any one of a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or an equivalent discrete or integrated logic circuit or many. In some examples, processing module 40 includes multiple components, such as one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs, and Any combination of other discrete or integrated logic circuits. Additionally, although shown as separate functional components in FIG. or a combination of multiple DSPs, one or more ASICs, one or more FPGAs, and/or other discrete or integrated logic circuits implementing the processing module 40 .

Processing module 40 may be in communication with memory 42 . Memory 42 may include computer readable instructions that, when executed by processing module 40 , cause processing module 40 and any other modules of LPD 10A to perform the various functions attributed to them herein. Memory 42 may comprise any volatile, nonvolatile, magnetic, or dielectric medium, such as random access memory (RAM), read only memory (ROM), nonvolatile RAM (NVRAM), electrically erasable Programmable ROM (EEPROM), flash memory, or any other memory device.

Stimulation module 44 and electrical sensing module 46 are electrically coupled to electrodes 16A, 16B. Processing module 40 is configured to control stimulation module 44 to generate and deliver pacing pulses to heart 24 (eg, right ventricle 22 in the example shown in FIG. 2 ) via electrodes 16A, 16B. Furthermore, the processing module 40 is configured to control the electrical sensing module 46 to monitor electrical signals from the electrodes 16A, 16B, thereby monitoring the electrical activity of the heart 24 . Electrical sensing module 46 may include circuitry to acquire electrical signals from electrodes 16A, 16B, as well as circuitry for filtering, amplifying, and otherwise processing the electrical signals. The electrical signals include intrinsic cardiac electrical activity, such as depolarization and repolarization of the ventricles and depolarization of the atria, and may be referred to as electrical cardiac signals or cardiac electrogram signals. Electrical detection module 46 detects ventricular depolarization or ventricular activation events within the electrical cardiac signal, and detects atrial depolarization or atrial activation events within the electrical cardiac signal.

In some examples, LPD 10A also includes sensor 48 . In some examples, sensors 48 include one or more accelerometers. In some examples, sensor 48 includes a plurality of accelerometers, such as three accelerometers, each of which is oriented to detect motion in a corresponding axis or vector direction. The axes or vectors may be orthogonal. In other examples, instead of or in addition to the one or more accelerometers (such as gyroscopes, mercury switches, or bonded piezoelectric crystals), sensor 48 may include one or more different sensors that generate signals based on motion. . In other examples, sensor 48 may be a pressure sensor instead of one or more accelerometers.

Communications module 50 may include any suitable hardware (eg, antenna), firmware, software, or any combination thereof for communicating with another device, such as programmer 18 (FIGS. 2 and 3) or a patient monitor. Under the control of processing module 40 , with the aid of an antenna included in communication module 50 , communication module 50 may receive downlink telemetry data from or send uplink telemetry data to other devices, such as programmer 18 or a patient monitor.

Memory 42 may include data recorded by LPD 10A, such as electrical cardiac signals, heart rate, information regarding detection of atrial sensing events or undersensing events, indications of undersensing, ventricular pacing efficiency, and the like. Under the direction of processing module 40 , communication module 50 may transmit data recorded by LDP 10A to another device, such as programmer 18 . Memory 42 may also store programming data that processing module 40 receives from another device, such as programmer 18 , via communication module 50 . The programming data stored in memory 42 may include, as examples, any AV interval length, any VV interval length, atrial systole detection delay period, and atrial or ventricular activation event detection window lengths described herein. The programmed data stored in memory 42 may additionally or alternatively include any of the thresholds described below, such as for detecting atrial and/or ventricular contraction, determining whether pacing is effective, or determining whether asynchronous pacing should be supported while pausing atrial Ventricular Synchronized Pacing. The programming data stored in memory 42 may additionally or alternatively include data used by processing module 40 to determine any of the values described herein, eg, based on determined parameters of heart 24, patient 26, or LPD 10A.

Figure 5 is a timing diagram illustrating normal conduction timing in a patient. The amount of time between an atrial activation event (paced or sensed) and a subsequent ventricular activation event may generally be referred to herein as the "A _ACT -V _ACT interval." In FIG. 5, the A _ACT -V _ACT interval has a consistent value of T1, while the interval between consecutive atrial events (ie, the AA interval) has a consistent value of T3. The interval between a ventricular activating event V _ACT and a subsequent atrial activating event A _ACT has a consistent value of T2, and the interval between successive ventricular activating events (ie, the VV interval) may always have a value of T4.

6A is an example illustrating a switch from a no-pacing sensing mode to an atrioventricular-synchronized pacing mode for controlling an LPD 10A (or another LPD) implanted in the right ventricle 22 in response to detection of ventricular insufficiency. Timing diagram of sexual technology. The timing diagram also demonstrates an exemplary technique for delivering atrioventricular synchronized pacing based on the detection of an atrial activation event. Activation of the atria can be intrinsic or paced depolarization of the atria, or mechanical contraction of the atria. Accordingly, processing module 40 may detect intrinsic depolarization of the atrium (e.g., far-field P-waves) by determining electrical sensing module 46, by determining that another device (e.g., another LPD implanted in the atrium) delivered Pacing pulses or atrial activation is identified by detecting mechanical contraction of the atria.

In some examples, in the no-pace sensing mode, processing module 40 may detect atrial activation event A _ACT ( FIG. 4 ), for example, in the electrical cardiac signal sensed by electrical sensing module 46 and, for example, upon sensing Ventricular sensing event V _S (eg, R wave) in the electrical cardiac signal of . Ventricular sensing event _VS may be indicative of an intrinsic depolarization of the ventricle (eg, right ventricle 22) in which LPD 10A is implanted. The processing module 40 may determine whether a ventricular sensed event V _S is detected within a ventricular event detection window W _VACT beginning at the atrial activation event _AS . This may indicate that the heart 24 exhibits normal intrinsic conduction.

In some examples, processing module 40 determines the duration of ventricular event detection window W _VACT based on stored data indicating consecutive atrial events over a predetermined number of most recent cardiac cycles (e.g., one to twelve heartbeats). The interval between activating events (ie, the AA interval). This historical AA interval data may be stored by memory 42 or the memory of another device. In some examples, the duration of the ventricular event detection window W _VACT may be one of: the average AA interval of the stored AA intervals, the median AA interval of the stored AA intervals, the stored AA interval The largest AA interval of the period, the shortest AA interval of the stored AA intervals, or the closest AA interval of the stored AA intervals. As another example, the duration of the ventricular event detection window _WVACT may be a predetermined percentage of the stored AA interval, such as 30% to 30% of the average or median AA interval of the last 12 heartbeat intervals. About 75% (eg, about 50%).

Additionally or conversely, the duration of the ventricular event detection window _WVACT may be selected by the clinician and may be independent of the patient's historical AA interval data. For example, in some examples, the duration of the ventricular event detection window W _VACT is preprogrammed as a fixed duration of about 300 milliseconds (ms) to about 700 ms (eg, about 500 ms). Processing module 40 may receive ventricular event detection window W _VACT from a clinician via, for example, a medical device programmer configured for communication with LPD 10A.

In yet other examples, processing module 40 determines the duration of the ventricular event detection window W _VACT based on stored data indicating the interval between consecutive atrial events for a particular number of most recent cardiac cycles (i.e., AA interval) and preprogrammed durations. For example, the processing module 40 may determine a first ventricular event detection window W _VACT based on stored AA interval data, eg, using the techniques described above, and may select the duration of the ventricular event detection window W _VACT as the first ventricular event detection window W The lesser of _VACT and the fixed programmed duration. In this way, at relatively slow heart rates, the processing module 40 uses a fixed, programmed duration as the ventricular event detection window _WVACT , and at higher heart rates may use a duration based on the actual heart activity of the patient 12. time.

In response to determining for a particular cardiac cycle that a ventricular sense event V _S is detected within a ventricular event detection window W _VACT , processing module 40 may cause LPD 10A to continue operating in the no-pace sensing mode for at least the next cardiac cycle. For example, as shown in FIG. 6A , processing module 40 detects atrial activating event 60A and ventricular sense event _62A detected within time period _T5 of atrial activating event 60A, the duration of time period T5 being less than the duration of the ventricular event detection The duration of the window W _VACT . Atrial activation event 60A and ventricular sensing event 62A are part of the same cardiac cycle. Accordingly, processing module 40 maintains the no-pace sensing mode for the next cardiac cycle. Processing module 40 detects a subsequent normal cardiac cycle in which ventricular sensing event 62B is detected by processing module 40 within ventricular event detection window W _VACT of atrial activation event 60B.

However, during the next cardiac cycle in the example shown in FIG. 6A , processing module 40 detects no ventricular induction event within ventricular event detection window W _VACT of atrial activation event 60C. Instead of controlling stimulation module 44 ( FIG. 4 ) to deliver pacing pulses to right ventricle 22 of heart 24 of patient 12 within the same cardiac cycle as atrial activation event 60C, processing module 40 may, however, delay delivery of ventricular pacing by at least one heartbeat. cycle. This may allow processing module 40 to, for example, sense the intrinsic conduction of heart 24 and determine whether heart 24 has returned to a normal heart rhythm without the aid of pacing therapy. In this manner, processing module 40 may be configured to control pacing therapy to favor intrinsic conduction.

In the example shown in FIG. 6A , to determine whether heart 24 has returned to a normal rhythm without the aid of pacing therapy, processing module 40 determines that within ventricular event detection window W _VACT of atrial activation event 60D of a subsequent cardiac cycle Whether a ventricular sense event V _S is detected (immediately following a cardiac cycle in which no ventricular sense event is detected within the ventricular event detection window W _VACT ). In response to detecting a ventricular sense event V _S within a ventricular event detection window W _VACT of an atrial activation event 60D of a subsequent cardiac cycle, processing module 40 may continue to operate LPD 10A in a no-paced sensing mode.

In some examples, processing module 40 may maintain the ventricular event detection window W _VACT in the next cardiac cycle. However, in other examples, as shown in FIG. 6A , processing module 40 may shorten the ventricular event detection window W _VACT in a cardiac cycle after a period in which no ventricular sensed event is detected (eg, in which a heartbeat is missed). In the example shown in FIG. 6A , the period in which no ventricular sensed events are detected is a cardiac cycle that includes an atrial activation event 60C. Shortening the ventricular event detection window _WVACT to a _shorter duration in cardiac cycles following periods in which no ventricular sensing events are detected may help provide more responsive cardiac pacing therapy , because shortening the ventricular event detection window _T may lead to a more timely ventricular pacing pulse V _P in subsequent cardiac cycles. In some examples, the ventricular event detection window _WVACT is about 70 ms to about 110 ms short, such as about 80 ms during a cardiac cycle including atrial activation event 60D and/or about 80 ms during a cardiac cycle including atrial activation event 60E .

However, in the example shown in FIG. 6A , processing module 40 does not detect ventricular sensing event V _S for a _{short period of the shortened ventricular event detection window W VACT} beginning at atrial activation event 60D. In response, processing module 40 switches LPD 10A from the non-paced sensing mode to the atrioventricular synchronized pacing mode. According to the exemplary technique for delivering atrioventricular synchronized pacing shown in FIG. 6A , no intrinsic ventricular sensing event is detected shortly after processing module 40 determines that the shortened ventricular event detection window _WVACT beginning at atrial activation event 60D After VS, processing module 40 may control stimulation module 44 to deliver a ventricular pacing pulse V _P 64A to a ventricle of heart 24 (eg, right ventricle 22 ) for a time period _T6 after the detected atrial activating event A _{ACT .} In the example shown in FIG. 6A , time period T ₆ has a duration that is shorter than or equal to shortened ventricular event detection window W _VACT , and may be less than or equal to ventricular event detection window W _VACT . Additionally, in the example shown in FIG. 6A , processing module 40 controls stimulation module 44 to deliver ventricular pacing pulse V _P 64A approximately 80 milliseconds after atrial activation event 60D. Other time intervals may also be used in other embodiments.

The processing module 40 may control the duration _T6 between the detection of the atrial activation _AS and the delivery of the next ventricular _pacing pulse VP. In some examples, processing module 40 selects the duration of time period _T6 based on the _AACT - _VS interval of two or more previous cardiac cycles (e.g., two cardiac cycles, three cardiac cycles, or more). time, the cardiac cycle may be the cardiac cycle immediately preceding the first cardiac cycle in which no ventricular sensing event is sensed. For example, the duration of time period _T6 may be equal to the average _AACT - _VS interval of two or more previous cardiac cycles. The average A _ACT -V _S interval may be a better representative of the current heart rate of the patient 26 than the preprogrammed atrioventricular synchronized pacing interval (A _ACT -V _P ) affecting the pacing interval. In this way, controlling the delivery of the ventricular pacing pulse _VP relative to the atrial activating event A _ACT based on the average A _ACT -V _S interval of two or more previous cardiac cycles may help to calm the patient's Heart rate, especially when compared to delivery of atrioventricular synchronized pacing using a preprogrammed atrioventricular synchronized pacing interval (A _{ACT -VP} ).

During the next cardiac cycle, processing module 40 detects atrial activation event 60E, determines whether a ventricular sense event is detected within a shortened ventricular event detection window _{WVACT shortly} beginning at atrial activation event 60E, and responds to a determination that If no ventricular sensing event is detected within the event detection window W _{VACT within a short} period of time or within a predetermined AV interval, the processing module ₄₀ controls the stimulation module 44 to _inject The ventricle (eg, the right ventricle 22) of the V P delivers a ventricular pacing pulse V _P 64A. However, if processing module 40 detects a ventricular sensed event within the shortened ventricular event detection window _WVACTshort or AV interval, processing module 40 may not control stimulation module 44 to deliver ventricular pacing during this particular cardiac cycle.

In some examples, once processing module 40 switches to the atrioventricular synchronized pacing mode, processing module 40 may apply a different ventricular event detection window _WVACTShort , which may be preprogrammed and associated with the atrioventricular synchronized pacing mode. For example, the ventricular event detection window W _VACT applied during the atrioventricular synchronized pacing mode may be about 80 ms to about 300 ms, such as about 130 ms, although other windows may also be used. Thus, in some examples of the technique shown in FIG. 6A , the ventricular event detection window W _VACT used by processing module 40 during a cardiac cycle including atrial activating event 60D may be different from that used during a cardiac cycle including atrial activating event 60E. The detection windows of ventricular events are different. As a result, in some examples, time period _T6 may differ in the cardiac cycle including events 60D, 60E.

In some examples, the AV interval may be equal to the ventricular event detection window W _VACT discussed with reference to FIGS. 6A , 6B, and 7 . In other examples, the AV interval may be smaller than the ventricular event detection window W _VACT . In other examples, the AV interval may be greater than the ventricular event detection window W _VACT . In some examples, the AV interval is preprogrammed, eg, selected by a clinician. For example, exemplary AV intervals include, for example, a range of about 80 ms to about 300 ms, such as about 130 ms, although other AV intervals may be used in other examples.

During operation in the atrioventricular synchronized pacing mode, processing module 40 may periodically perform intrinsic conduction checks to determine whether heart 24 has returned to normal intrinsic conduction. For example, the processing module 40 can control the stimulation module 44 to stop the ventricular pacing (V _P ) for at least one cardiac cycle (for example, one cardiac cycle, two cardiac cycles or more than three cardiac cycles), so as to determine whether the atrial activation event A An intrinsic ventricular sensing event V _S is detected within the ventricular event detection window W _VACT of _ACT .

In the example shown in FIG. 6A , processing module 40 does not detect ventricular activation within a _short period of ventricular event detection window W VACT of atrial activating event A _ACT 60F or within a _{short period of ventricular event detection window W VACT} of atrial activating event A _ACT 60G Event _VS. In response to making this determination, processing module 40 may continue to control stimulation module 44 to deliver ventricular pacing pulses to right ventricle 22 in the atrioventricular synchronized pacing mode. As shown in FIG. 6A , in this mode, processing module 40 may control stimulation module 44 to deliver ventricular pacing pulse V _P 64C to patient 26 following an atrial activation event A _ACT 60G of a subsequent cardiac cycle.

In instances where processing module 40 detects intrinsic ventricular sensed event _{VS shortly within ventricular event detection window WVACT beginning} at corresponding atrial activation event AACT 60E, processing module 40 may switch LPD 10A back to no pacing sensing mode. In other examples, in response to determining for a predetermined threshold number (e.g., stored by memory 42) of consecutive cardiac cycles that an intrinsic ventricular sensing event _VS is detected within a ventricular event detection window _AACT of a corresponding atrial activation event _AACT , Processing module 40 may switch LPD 10A to a no-pace sensing mode. The threshold number of cardiac cycles may be, for example, two, three, four or more.

Additionally, in some examples, processing module 40 may switch LPD 10A to a non-paced sensing mode in response to determining that intrinsic conduction was observed during the intrinsic conduction check. In some examples, processing module 40 temporarily places LPD 10A in no-paced sensing mode for at least one cardiac cycle (eg, one cardiac cycle or two cardiac cycles) in order to perform an intrinsic conduction check. In response to determining that intrinsic conduction was observed during at least one cardiac cycle, processing module 40 may control LPD 10A to remain in the no-pace sensing mode.

Processing module 40 may perform intrinsic conduction checks at any suitable interval that may remain the same or increase over time. For example, after switching to the atrioventricular synchronized pacing mode, processing module 40 may perform conduction checks at progressive time intervals that increase over time. As one example, processing module 40 may perform an intrinsic conduction test one minute after switching LPD 10A to the atrioventricular synchronized pacing mode. If intrinsic conduction is not tested, processing module 40 may continue to operate LPD 10A in AV synchronized pacing mode and perform an intrinsic conduction check two minutes after the first check. If no intrinsic conduction is detected at that point, processing module 40 may continue to operate LPD 10A in the atrioventricular synchronized pacing mode and perform another intrinsic conduction check four minutes after the second check. This can be continued for any suitable progressive time interval.

FIG. 6B is a diagram illustrating another example for controlling the switching of an LPD 10A (or another LPD) implanted in the right ventricle 22 from a no-pacing sensing mode to an atrioventricular-synchronized pacing mode in response to detection of ventricular insufficiency. Timing diagram of an exemplary technique. As with the technique described with respect to FIG. 6A , processing module 40 controls LPD 10A to never report a ventricular sense event to patient 26 in response to determining for one or more cardiac cycles that a ventricular sense event was not detected within the ventricular event detection window W _VACT of an atrial activation event. The no-pace sensing mode of heart 24 delivering pacing therapy is switched to the atrioventricular synchronized pacing mode. For example, in FIG. 6B, processing module 40 detects no ventricular sensing event within ventricular event detection window W _VACT of atrial activation event 60C. Processing module 40 may delay delivery of the ventricular pace by at least one cardiac cycle during that cardiac cycle that includes atrial activation event 60C. Thus, as shown in Figure 6B, there is no ventricular pacing pulse following the atrial activating event 60C.

As with the technique described with respect to FIG. 6A , processing module 40 detects no ventricular sensed event V _S for a _{short period of the shortened ventricular event detection window W VACT} beginning at atrial activation event 60D and, in response, controls LPD 10A according to the atrioventricular Synchronous pacing mode delivers pacing pulse V _P 64A. However, in contrast to the techniques described with respect to FIG. 6A , in the example shown in FIG. 6B , processing module 40 does not control LPD 10A to remain in AV synchronized pacing mode after delivery of pacing pulse V _P 64A. Instead, processing module 40 controls LPD 10A to revert (eg, switch) back to a no-pace sensing mode in which LPD 10A does not deliver any pacing therapy to patient 26 .

As shown in FIG. 6B , after LPD 10A delivers pacing pulse VP _64A , processing module 40 detects atrial activation event 60H while LPD 10A is in the no-pace sensing mode and determines whether shortening begins at atrial activation event 60H. The ventricular event detection window W _{VACT occurs within a short} period of the atrial sensing time Vs. However, in the example shown in FIG. 6B , the processing module 40 does not detect a ventricular sense event V _S within the shortened ventricular event detection window W _VACTShort . However, because processing module 40 controls LPD 10A according to the no-pace sensing mode, processing module 40 does not sense ventricular sense for a _{short period of time in response to the shortened ventricular event detection window WVACT} beginning at atrial activation event 60H. Stimulation module 44 is controlled to deliver ventricular pacing pulses in response to event _VS. In this way, LPD 10A can miss a heartbeat. Conversely, processing module 40 may generate a sense _undersense , for example, by incrementing a sense undersense counter, in response to determining that a ventricular sense event VS has not been detected within the shortened ventricular event detection window _WVACT beginning at atrial activation event 60H. instruct. Processing module 40 may then detect a subsequent atrial activation event 60I according to the no-pace sensing mode and determine whether a ventricular sensed event V _S is detected within the shortened ventricular event detection window W _{VACT short} beginning at atrial activation event 60I .

According to the exemplary technique shown in FIG. 6B, after processing module 40 determines that a shortened ventricular event detection window _WVACT beginning at atrial activation event 60I has not detected an intrinsic ventricular sensing event VS for _{a short} period of time, processing module 40 may control Stimulation module 44 delivers ventricular pacing pulse V _P 64D to a ventricle of heart 24 (eg, right ventricle 22 ) for time period T ₆ after atrial activating event 60I. The processing module 40 may also generate an undersensing indication, eg, by incrementing an undersensing counter.

In the example shown in FIG. 6B , processing module 40 implements an "X of Y" counter, where in some examples "X" may be four undersensed indications and "Y" may be four, five, or four. one, six or more. In other examples, the "X" may indicate the number of "missed beats," eg, the number of cardiac cycles in which no ventricular event (whether sensed or paced) was detected. Thus, in some examples, "X" may be two undersensing indications, and "Y" may be three, four, five, six or more, such as four in some examples.

After processing module 40 increments the counter in response to determining that a ventricular sense event VS has not been detected for a _{short time within the shortened ventricular event detection window WVACT beginning} at atrial activation event 60I, processing module 40 may determine that the counter indicates a change from "X" undersensing indications are detected in "Y" cardiac cycles. Thus, in response, processing module 40 may switch LPD 10A to the AV-synchronized pacing mode indefinitely, e.g., until a conduction check indicates detection of intrinsic conduction or until another mode change is made (e.g., until processing module 40 determines that LPD 10A Switching to asynchronous pacing mode would be desired). Unlike a cardiac cycle that includes an atrial activation event 60D, processing module 40 may not revert LPD 10A back to the no-pace sensing mode after LPD 10A delivers a ventricular pacing pulse 64D. Instead, processing module 40 may control stimulation module 44 to continue delivering ventricular pacing pulses according to the atrioventricular synchronized pacing mode.

For example, after switching LPD 10A to an atrioventricular synchronized pacing mode, processing module 40 may detect atrial activation event 60J and determine whether a ventricular activation event was detected within the shortened ventricular event detection window _WVACT that began at atrial activation event 60J Sensing events. In response to determining that a ventricular sensed event is not detected within the shortened ventricular event detection window W V _ACT or within a predetermined AV interval, the processing module 40 controls the period of time after the detected atrial activation event A _ACT 60J by the stimulation module 44 Ventricular pacing pulse V _P 64E is delivered to a ventricle of heart 24 (eg, right ventricle 22 ) in T ₆ . In contrast, in certain instances where processing module 40 reverts LPD 10A back to the no-pace sensing mode, stimulation module 44 does not deliver ventricular pacing pulse VP _64E , and heart 24 may miss a beat.

FIG. 7 is a flowchart of an exemplary technique for operating LPD 10A. In the technique shown in FIG. 7, processing module 40 switches LPD 10A between a no-pace sensing mode and an atrioventricular-synchronized pacing mode. Although the techniques shown in FIG. 7, as well as other techniques described herein, are primarily described as being performed by processing module 40, in other examples, the techniques described herein may be performed by another processing module (e.g., another implanted device or an external device). A processing module such as a medical device programmer) is executed alone or in combination with the processing module 40. Furthermore, while the right atrium 28 and right ventricle 22 are primarily referred to herein, in other examples, the devices, systems and techniques described herein may also be used to control pacing therapy delivered to the left ventricle, sense left atrium activity or both.

According to the technique shown in FIG. 7 , processing module 40 identifies atrial activation event A _ACT while operating LPD 10A in an unpaced sensing mode ( 70 ). The atrial activation event may be, for example, an intrinsic or paced depolarization of the right atrium 28 or a mechanical contraction of the right atrium 28 . Processing module 40 may determine whether a ventricular sensed event VS is detected within a ventricular event detection window _WVACT beginning at an atrial activation event _AACT (72) based on the electrical cardiac signal sensed by electrical sensing module 46 ₍ e.g., intrinsic ventricular depolarization). In response to determining that a ventricular sense event VS was detected within the ventricular event detection window _{WVACT (} "YES" branch of block 72), processing module 40 may reset the ventricular event counter and, in the no-paced sense mode (70, 72) Next, continue to sense the heart activity.

The ventricular event counter may be used to count cardiac cycles in which no ventricular depolarization V _ACT is detected within a ventricular event detection window W V _ACT beginning at a corresponding atrial activation event A _ACT . In the example shown in FIG. 7, the ventricular event counter may be used to count cardiac cycles in which no ventricular depolarization V _ACT is detected within the ventricular event detection window W V _ACT . The number of cardiac cycles may be the number of cardiac cycles ("X") within a predetermined number of cardiac cycles ("Y"). In the latter example, the counter may be referred to as an "X of Y" type counter, where "X" indicates the number of cardiac cycles in which no ventricular depolarization V _ACT was detected, and "Y" indicates a predetermined number of consecutive Cardiac cycle.

In other examples, the ventricular event counter may be used to count the number of cardiac cycles during a predetermined time period during which no ventricular depolarization V _ACT is detected within a ventricular event detection window W V _ACT . Thus, in other examples of the technique shown in FIG. 7, processing module 40 may not reset a ventricular event in response to detecting a ventricular sense event _VS within a ventricular event detection window _WVACT during one cardiac cycle. counter (74), however, processing module 40 may reset the ventricular event counter at the end of a predetermined period of time.

In response to determining that a ventricular sense event V _S was not detected within the ventricular event detection window W _VACT (branch "NO" of block 72 ), processing module 40 increments a ventricular event counter ( 76 ). The counters may be implemented as software, hardware, firmware, or any combination thereof. For example, when the processing module 40 increments the counter, the processing module 40 may generate an error generated by the processing module 40 and generated by the memory 42 of the LPD 10A or the memory of another device (e.g., another implanted device or an external medical device programmer). ) Stored flags, values or other parameters or indications. As another example, the counter may be implemented by register-type circuitry, and processing module 40 may cause a state change of the register-type circuitry in order to increment or otherwise manage the counter. Counters with other configurations can also be used.

After incrementing the ventricular event counter (76), processing module 40 may determine whether the counter value is greater than or equal to the ventricular event threshold (78). The ventricular event threshold may indicate no detection within the ventricular event detection window W _VACT or within the shortened ventricular event detection window W _VACT following an atrial activation event before the LPD 10A delivers ventricular pacing therapy in the atrioventricular synchronized pacing mode. The number of cardiac cycles in which a ventricular event was detected. In some examples, as shown in FIG. 6A , the ventricular event threshold is one. In other examples, the ventricular event threshold may be greater than one, such as two, three or four or more.

The ventricular event threshold may be determined by a clinician as a value indicative of intrinsic AV conduction loss, and may be selected to be low enough to configure LPD 10A to provide responsive switching between modes of operation and provide responsive rhythm management therapy. The ventricular event threshold may be stored by memory 42 of LPD 10A or a memory of another device (eg, a medical device programmer) that may communicate with processing module 40 via communication module 50 ( FIG. 4 ).

In response to determining that the counter value is less than the ventricular event threshold ("No" branch of block 78), processing module 40 may continue to sense cardiac activity in a no-pace sensing mode (70, 72). On the other hand, in response to determining that the counter value is greater than or equal to the ventricular event threshold ("YES" branch of block 78), processing module 40 may cause LPD 10A to switch from the no-pacing sensing mode to atrioventricular-synchronized pacing mode(80). An example of the atrioventricular synchronized pacing mode is described with reference to FIG. 8 . A counter value greater than or equal to the ventricular event threshold may indicate the presence of AV block.

In some examples, processing module 40 may reset the counter to zero whenever a ventricular sense event V _S is detected within ventricular event detection window W _VACT . In other examples, processing module 40 increments the ventricular event counter for non-consecutive cardiac cycles in which no ventricular depolarization is detected within the ventricular event detection window _WVACT , and at other times (e.g., if between two or Detection of ventricular depolarization within the ventricular event detection window W _VACT for more consecutive cardiac cycles resets the counter. As another example, processing module 40 may manage the ventricular event counter to track failures to detect within a ventricular event detection window W _VACT within a predetermined time frame (eg, within 30 seconds, 1 minute, or more). The number of ventricular sensing events _VS , or as an "X of Y" counter. For example, processing module 40 may increment, for each case, the ventricular event counter for a predetermined period of time during which no ventricular depolarization is detected within the ventricular event detection window _WVACT , and reset the ventricular event counter at the end of the time period. counter. As another example, the processing module 40 may increment the ventricular event counter for each instance of a predetermined number of immediately preceding cardiac cycles in which no ventricular depolarization was detected within the ventricular event detection window W _VACT .

In some examples of the techniques shown in FIG. 7 , processing module 40 may generate a ventricular event indication in response to determining that a ventricular sensed event is not detected within detection window W _VACT and may generate a ventricular event indication by storing the ventricular event indication in the LPD The ventricular event counter is incremented in the memory 42 of the 10A or in the memory of another device. Processing module 40 may reset the ventricular event counter by deleting the stored ventricular event indication. Processing module 40 may also determine whether the ventricular event counter value is greater than or equal to a threshold by at least determining whether the number of stored ventricular event indications is greater than or equal to the ventricular event threshold (116).

The configuration of LPD 10A described with respect to FIGS. 6A, 6B, and 7, wherein LPD 10A does not deliver ventricular pacing during a cardiac cycle in which processing module 40 does not detect a ventricular event, may allow electrical sensing module 46 to synchronize pacing atrioventricularly. Intrinsic activity of the heart 24 is sensed for at least one complete heartbeat prior to delivery of a ventricular pacing pulse in the mode. In this manner, processing module 40 may take time to sense a ventricular activation event, for example allowing heart 24 to restore intrinsic conduction before LPD 10A delivers a ventricular pacing pulse, which may or may not correspond to patient 26's pacing pulse. current heart rate. By being configured for missing one or more heartbeats, LPD 10A may be configured to facilitate intrinsic conduction of heart 24 by giving LPD 10A an opportunity to sense intrinsic conduction of heart 24 before stimulation module 44 delivers ventricular pacing. . This may help the heart 24 stay in sync.

8 is a flowchart of an exemplary technique for delivering pacing pulses to the ventricles of heart 24 according to the atrioventricular synchronized pacing mode. The processing module 40 identifies an atrial activation event (70) and determines whether an intrinsic ventricular sensing event _VS is detected after the atrial activation event, e.g., within the AV interval from the detection of the atrial activation event or within the ventricular event detection window _WVACT (eg, R waves).

In response to determining that a ventricular sense event was not detected after the atrial activation event (branch "NO" of block 84), processing module 40 may control stimulation module 44 to generate and deliver a pacing pulse to right ventricle 22 of heart 24 ( 88). In response to determining that a ventricular sensing event was detected after the atrial activation event ("YES" branch of block 84), LPD 10A may not deliver ventricular pacing pulses, and instead processing module 40 may continue to monitor cardiac activity of patient 26 (70, 84). For patients with intermittent AV nodal conduction, it may be more preferable for LPD 10A to inhibit ventricular pacing according to the technique shown in FIG. ) with intrinsic ventricular depolarization.

In some examples, LPD 10A may sense insufficient atrial activity (e.g., intrinsic depolarization or atrial pacing activity) of heart 24, which may affect ventricular pacing when LPD 10A is operating in an atrioventricular synchronized pacing mode. Delivery of pulses (eg, as shown in Figure 8). According to some examples described herein, LPD 10A is configured to automatically switch from an atrioventricular synchronous pacing mode to an asynchronous ventricular pacing mode (in some cases without user intervention) in response to detection of an atrial undersensing event.

FIG. 9 is a timing diagram illustrating an example of asynchronous ventricular pacing and is described with reference to FIG. 10 , which is a flowchart of an exemplary technique for delivering asynchronous ventricular pacing. In the technique shown in FIG. 10, processing module 40 identifies a ventricular activation event V _ACT (90), which may be the delivery of a ventricular pacing pulse or an intrinsic depolarization of the right ventricle 22 (e.g., by sensing R wave in the electrical cardiac signal sensed by module 46). The processing module 40 determines whether intrinsic depolarization of the right ventricle 22 has been detected during the VV interval from when ventricular activation was detected (e.g., when a previous intrinsic ventricular depolarization was detected or a previous ventricular pacing pulse was delivered). Polarization (92).

The VV interval can be of any suitable length. In some examples, processing module 40 determines the VV interval based on the sensed cardiac activity of patient 26 and stores the interval in memory 42 . For example, processing module 40 may determine the VV interval as a sequence of ventricular activation events (e.g., a sequence of intrinsic ventricular depolarizations detected by electrical sensing module 44) a certain number of cardiac cycles immediately preceding the present cardiac cycle The average or median time between. The certain number may for example be two or more, such as six, ten, twelve, twenty or thirty. In some examples, the processing module uses the VV interval to time delivery of the ventricular pacing pulses delivered in the asynchronous ventricular pacing mode. In this case, the VV interval may be slightly longer than the patient's 26 heart rate, which may be determined from the sensor data.

In other examples, processing module 40 may use a pre-programmed VV interval. However, this may be lower than the patient's current heart rate, which may result in a relatively sudden change in the patient's 26 heart rate, which may be undesirable. Controlling the timing of ventricular pacing pulses VP delivered according to the asynchronous ventricular pacing mode based on the _VV interval, which is determined based on the sensed cardiac activity of the patient 26, may help calm the patient 26. heart rate, especially when compared to controlling the timing of pacing pulses based on a preprogrammed rate.

In some examples, processing module 40 determines the VV interval to be the greater of a VV interval determined based on sensed cardiac activity of patient 26 or a preprogrammed rate. This may enable processing module 40 to provide some minimum pacing rate, which may further assist in stabilizing patient 26's heart rate.

In any of the above examples, processing module 40 may also modify the VV interval based on detected changes in heart rate of patient 26 . For example, processing module 40 may increase the VV interval as the heart rate decreases and decrease the VV interval as the heart rate increases. In this manner, processing module 40 may provide rate adaptive asynchronous ventricular pacing.

In response to determining that an intrinsic depolarization of the right ventricle 22 was detected during the VV interval ("Yes" branch of block 92), processing module 40 may determine that the sensed intrinsic depolarization of the right ventricle 22 is a ventricular activation (90 ) and determine whether a subsequent intrinsic depolarization of the right ventricle 22 is detected during the VV interval (92). For example, in the timing diagram shown in FIG. 9, after processing module 40 identifies ventricular activating event V _ACT 98, processing module 40 may determine the VV beginning at ventricular activating event V _ACT 98 based on the sensed electrical cardiac signal. Intrinsic depolarization of the right ventricle 22V _S 100 was detected during the interval. The processing module 40 may then determine whether an intrinsic depolarization of the right ventricle 22 is detected during the VV interval beginning at the intrinsic depolarization of the right ventricle 22V _S 100 ( 92 ).

In response to determining that no intrinsic depolarization of the right ventricle 22 is detected during the VV interval ("no" branch of block 92), processing module 40 may control stimulation module 44 to deliver a ventricular pacing pulse to right ventricle 22 (94). For example, in the timing diagram shown in FIG. 9 , no intrinsic depolarization of the right ventricle is detected during the VV interval beginning at ventricular sense event _VS 100 as determined by processing module 40 based on the sensed electrical cardiac signal. 22Vs, the processing module 40 may control the stimulation module 44 to deliver the ventricular pacing pulse V _P 102 to the right ventricle 22 . The ventricular pacing pulse may be delivered at the end of the VV interval beginning at the previously detected ventricular activation event _VS 100 .

Processing module 40 may then identify ventricular pacing pulse _VP 102 as a ventricular activation event (90), and determine whether intrinsic depolarization of right ventricle 22 is detected during the VV interval beginning at ventricular pacing pulse _VP 102 (92). In the example timing diagram shown in FIG. 9 , the processing module 40 determines based on the sensed electrical cardiac signal that no intrinsic depolarization of the right ventricle 22V was detected during the VV interval beginning at the ventricular pacing pulse _VP 102. _S. Accordingly, processing module 40 may control stimulation module 44 to deliver ventricular pacing pulse V _P 104 to right ventricle 22 .

11 is a flowchart of an example technique for switching LPD 10A (or another LPD) from an atrioventricular synchronous pacing mode to an asynchronous ventricular pacing mode in response to detection of an atrial undersensing event. When the switching is performed, processing module 40 controls stimulation module 44 to cease delivery of pacing pulses to right ventricle 22 in an atrioventricular synchronized pacing mode with ventricular pacing pulses timed as atrial activation events, and controls stimulation module 44 to Pacing pulses are delivered to right ventricle 22 in an asynchronous ventricular pacing mode, where the ventricular pacing pulses are timed relative to ventricular activation events.

According to the technique shown in FIG. 11 , when processing module 40 controls stimulation module 44 to deliver ventricular pacing pulses to right ventricle 22 of heart 24 of patient 26 according to an atrioventricular synchronized pacing pattern, processing module 40 may detect a ventricular activation event V _ACT (91), and determining whether an atrial activating event _AACT is detected within an atrial event detection window _WAACT starting at a previous atrial activating event _AACT (110). In other examples, the atrial event detection window W _AACT may begin at a previous ventricular activation event, which may be, for example, a ventricular pacing pulse (V _P ) or an intrinsic ventricular depolarization (V _S ) (e.g., delivery of R-waves detected within the sensed electrical cardiac signal). In some examples, LPD 10A may be configured to detect contraction of right ventricle 22 based on the motion signal, and to identify activation of the ventricle based on the detected contraction of the ventricle. Similarly, the atrial activating event may be, for example, an intrinsic atrial depolarization sensed by the LPD 10A, an atrial pacing event, or a mechanical contraction of the atrium.

The atrial event detection window _WAACT may define a listening period during which processing module 40 analyzes sensed electrical cardiac signals (or another physiological signal) to detect atrial activation events. In some examples, the duration of the atrial event detection window _WAACT is based on the average or median AA interval of a predetermined number of past cardiac cycles, such as the past 6 to 12 cardiac cycles. In some examples, the atrial event detection window W _AACT is between about 350 ms and about 1200 ms. In yet other examples, the duration of the atrial event detection window W _AACT is based on the average or median VV interval of a predetermined number of past cardiac cycles, such as the past 6 to 12 cardiac cycles.

In response to detecting an atrial activation event A _ACT within the atrial event detection window W _AACT (branch "YES" of block 110 ), the processing module 40 may reset the tracking function for the absence of atrial activation within the corresponding atrial event detection window W _AACT A counter (112) of the number of cardiac cycles for event A _ACT , referred to herein as an undersensing counter. In some examples, the undersensing counter may count a plurality of undersensing indications and may be configured in the same manner as the ventricular event counter (described with respect to FIG. 7 ). In some examples, the _undersensing counter may be used to count the number of consecutive cardiac cycles in which an atrial activation event _AACT is not detected within a corresponding atrial event detection window WAACT, and in some examples processing module 40 The counter can be reset by returning the counter to zero. In other examples, the undersensing counter may be used to count the number of cardiac cycles for which the atrial activation event _AACT was not detected within a predetermined period of time or within a corresponding atrial event detection window _WAACT to count. In some examples where an "X of Y" type counter is used, processing module 40 may remove any counts included within the "X" value corresponding to an indication of undersensing that occurred "Y" previous cardiac cycles before. to reset the counter. In other examples of the technique shown in FIG. 11 , processing module 40 may not reset the undersensing counter (112) in response to detecting an atrial activation event A _ACT within the atrial event detection window in one cardiac cycle. ), however, the processing module 40 may reset the undersensing counter at the end of the predetermined time period.

Processing module 40 may identify the next ventricular activation event or the end of the next atrial activation event detection window ( 91 ) and repeat the technique shown in FIG. 11 . In response to determining that an atrial activation event A _ACT is not detected within the next atrial event detection window _WA ACT ("No" branch of block 110), processing module 40 generates an undersensing indication and increments an undersensing counter (114). In some cases, an atrial activation event may occur, but may be detected by the processing module 40 outside of the atrial event detection window after the end of the atrial event detection window _WAACT . In other cases, an atrial activation event may not occur or may not be detected by the processing module until the next ventricular activation event is detected. In either case, it may be determined that the lack of detection of an atrial activation event is not within the atrial event detection window _WAACT and is the result of insufficient atrial sensing by the LPD 10A.

Processing module 40 determines whether the undersensing counter value is greater than or equal to an undersensing threshold (116). The undersensing threshold may be indicative of atrial activation beginning immediately before a detected atrial activation event A _ACT before processing module 40 detects an atrial undersensing event and controls LPD 10A to switch to an asynchronous ventricular pacing mode. Event Detection Window W _AACT The number of cardiac cycles in which no atrial activation event was detected. The undersensing threshold may be stored by the memory 42 of the LPD 10A or the memory of another device that may be in communication with the processing module 40 (eg, a medical device programmer).

In some examples, the undersensing threshold is one. In other examples, the undersensing threshold may be greater than one, such as two, three or four or more. The undersensing threshold may be selected to be low enough to configure LPD 10A to switch modes of operation responsively to provide responsive cardiac rhythm management therapy, but high enough to provide time for LPD 10A to determine whether the LPD 10A will ultimately be controlled by the LPD. 10A senses an atrial activation event during a time period during which LPD 10A can still deliver effective atrioventricular synchronized pacing. This may allow heart 24 to maintain intrinsic conduction because if sensing module 40 of LPD 10A senses an atrial activation event, LPD 10A may continue to deliver atrioventricular synchronized pacing, which facilitates synchronization of right ventricle 22 with right atrium 28 .

In atrioventricular synchronized pacing mode, processing module ₄₀ controls stimulation _module 44 to generate and deliver ventricular pacing pulses to right ventricle 22 (or at Left ventricle in other examples). In this manner, the atrial activation event A _ACT can be used to time the delivery of ventricular pacing pulses in the atrioventricular synchronized pacing mode. In some examples, time period T6 is based on stored VV interval data. For example, time period _T6 may be selected such that the VV interval of this cardiac cycle is substantially equal (eg, equal or approximately equal) to the average or median VV interval of a number of immediately preceding cardiac cycles.

During a cardiac cycle in which processing module 40 does not detect atrial activation event _AACT within atrial event detection window _WAACT (branch "No" of block 110), processing module 40 may, via stimulation module 44, based on previous ventricular pacing pulses Controls the timing of ventricular pacing pulses. As shown in FIG. 12, for example, processing module 40 may control stimulation module 44 to deliver a ventricular pacing pulse for a period of time following a previous ventricular pacing pulse (or other ventricular activation event) that is substantially equal to "VV Interval + Deviation". "VV interval + deviation" may be substantially equal to the mean or median VV interval of the number of immediately preceding cardiac cycles plus a deviation that adds time to the VV interval. As a result, pacing pulses may be delivered after time period _T6 and still be delivered in a timely manner. In some cases, the additional amount of time is about 50 milliseconds to about 250 milliseconds, such as about 100 milliseconds, or a percentage of the VV interval.

By timing the delivery of ventricular pacing pulses based on detected atrial activation events in the atrioventricular synchronous mode, processing module 40 may time the ventricular pacing pulses based on the current heart rate of patient 26 .

If the undersensing counter value is not greater than or equal to the undersensing threshold, processing module 40 may determine that no atrial undersensing event has been detected. Accordingly, in response to determining that the undersensing counter value is less than the undersensing threshold ("No" branch of block 116), processing module 40 may continue to monitor cardiac activity of patient 26 using the technique shown in FIG. Undersensing event. However, in some examples, processing module 40 may not detect a ventricular activating event if, for example, stimulation module 44 does not deliver a ventricular pacing pulse during a cardiac cycle in which no atrial activating event is detected ( 91 ). Therefore, instead of detecting a ventricular activation event, processing module 40 may identify the end of the previous atrial event detection window W _AACT (91) and determine that the modified atrial event detection window W _AACT beginning at the end of the atrial event detection window W _{AACT modifies} Whether an atrial activation event was detected in the In some examples, the modified atrial event detection window W _{AACT modified} may have a longer duration than the atrial event detection window W _AACT .

In some examples, the atrial event detection window _WAACT has a duration based on the VV interval of previously detected ventricular activation events. For example, the atrial event detection window may be the longest of the last two, three, four, or more (e.g., ten or more) VV intervals of those cardiac cycles in which the processing module 40 detected an atrial activation event. , minimum or average duration plus an additional amount of time.

Modified Atrial Event Detection Window _{WAACT The modification} may be the atrial event detection window _WAACT plus an additional amount of time that causes the heart rate of patient 26 to vary. The deviation may be about 30 ms to about 100 ms, such as about 50 ms or about 100 ms, or may be in the range of about 50 ms to about 150 ms. In other examples, the deviation may be about 50 ms to about 150 ms, which may be in the range of 10 to 20 beats per minute.

The processing module 40 may store the atrial event detection window _WAACT , the modified atrial event detection window _{WAACTmodified} , the AA interval for the most recently detected atrial activation event, the deviations mentioned above or any combination thereof.

Processing module 40 may detect an atrial undersensing event in response to determining that the undersensing counter value is greater than or equal to the undersensing threshold ("YES" branch of block 116). As shown in FIG. 11 , in response to determining that the undersensing counter value is greater than or equal to the undersensing threshold ("YES" branch of block 116), processing module 40 may cause LPD 10A to switch from the atrioventricular synchronous pacing mode to the asynchronous pacing mode. Ventricular pacing modes (118). Accordingly, processing module 40 may control delivery of ventricular pacing pulses to right ventricle 22 of heart 24 of patient 26 using an asynchronous ventricular pacing mode (eg, as shown and described with respect to FIGS. 9 and 10 ).

In some examples, processing module 40 generates an indication of the undersensing event and stores the indication in memory 42 or a memory of another device. The indication may be, for example, a flag, value or other parameter. The number and timing of undersensing events can be used by a clinician at a later time for assessing patient condition or treatment.

In some examples of the techniques shown in FIG. 11 , processing module 40 may generate the sense _undersensing indication in response to determining that atrial activation event A _ACT is not detected within a corresponding atrial event detection window W The undersensing counter is incremented by storing the undersensing indication in the memory 42 of the LPD 10A or in another device's memory. The processing module 40 may reset the stored sensory undersensing indications, for example, by deleting the stored sensory undersensing indications or by deleting the stored sensory undersensing indications that occurred before "Y" previous cardiac cycles when an "X of Y" type counter is used. The undersensing counter described above. Processing module 40 may also determine whether the undersensing counter value is greater than or equal to a threshold by at least determining whether the number of stored undersensing indications is greater than or equal to the undersensing threshold (116).

12 is a timing diagram illustrating an example application of the technique of FIG. 11 for switching from an atrioventricular synchronous pacing mode to an asynchronous ventricular pacing mode in response to detection of an undersensing event. In the example shown in Figure 12, the ventricular activating events are shown as ventricular pacing pulses _VP , but in other examples at least some of the ventricular activating events may be intrinsic ventricular depolarizations.

As shown in FIG. 12, the processing module 40 may control the delivery of ventricular pacing pulses to the right ventricle 22 in the atrioventricular synchronized pacing mode. For example, as described with respect to FIG. 7, processing module 40 may detect atrial activation event A _ACT 120 based on electrical cardiac signals sensed by electrical sensing module 46, based on detection of delivered atrial pacing pulses, or using another technique. . Processing module 40 may determine whether intrinsic ventricular depolarization is detected within a ventricular sensing event detection window W _VACT or W _{ACT short} (not labeled in FIG. 12 ), for example using the technique shown in FIG. 8 . In the example shown in FIG. 12 , during cardiac cycle 121A, processing module 40 determines that no intrinsic ventricular depolarization has been detected within the ventricular sensed event detection window, and controls stimulation module 44 to respond to a detected atrial activation event. A ventricular pacing pulse V _P 122 is delivered to the right ventricle 22 during time period T ₆ following A _ACT 120 .

In the next cardiac cycle 121B (immediately following cardiac cycle 121A), processing module 40 determines that atrial activation event A _ACT 124 is detected within atrial event detection window W _AACT beginning at atrial activation event 120 ( 110 ). According to the technique shown in FIG. 11 , processing module ₄₀ may then reset the _undersensing counter ( 112 ) and control stimulation module 44 to deliver Ventricular Pacing Pulse V _P 126. Similarly, in subsequent cardiac cycle 121C, processing module 40 determines that atrial activation event A _ACT 128 was detected within atrial event detection window W _AACT of previous cardiac cycle 121B ( 110 ). Processing module 40 may then reset the undersensing counter ( 112 ) and control stimulation module 44 to deliver ventricular pacing pulse V _P 130 to right ventricle 22 during time period T ₆ after detected atrial activation event A _ACT 128 .

In subsequent cardiac cycle 121D, processing module 40 determines that atrial activating event A _ACT was not detected within modified atrial event detection window W _AACT beginning at atrial activating event A _ACT 128 (branch "no"). A longer atrial event detection window may be used in this case to provide processing module 40 with a sufficiently long listening period for atrial activation events. For example, in some examples, the longer atrial event detection window may be greater than the average AA interval of a predetermined number (eg, 5, 10, or more) of immediately preceding cardiac cycles. As another example, a longer atrial event detection window may have a predetermined preprogrammed duration.

In response to determining that an atrial activation event _AACT is not detected within the modified atrial event detection window _WAACT , processing module 40 may increment (114) the undersensing counter and determine whether the undersensing counter value is greater than or Equal to the undersensing threshold (116). In the example shown in FIG. 12 , processing module 40 determines that the undersensing counter value is not greater than or equal to the undersensing threshold in cardiac cycle 121D (branch "NO" from block 116 ). Accordingly, processing module 40 may control stimulation module 44 to deliver ventricular pacing pulse V _P 132 to right ventricle 22 , which is timed as ventricular pacing pulse 130 immediately preceding cardiac cycle 121C. In the example shown in FIG. 12 , stimulation module 44 delivers ventricular pacing pulse V _P 132 for a period of time following ventricular pacing pulse 130 , wherein the period of time is substantially equal to (eg, equal to or approximately equal to) between VV period plus bias (VV interval + bias). The deviation may be 30ms to about 100ms, such as about 50ms or about 100ms. Thus, the VV interval is only slightly prolonged due to undersensing of the atria.

However, in subsequent cardiac cycle 121E, processing module 40 determines that no atrial activation event A _ACT was detected within the modified atrial event detection window W _{AACT that} began at the end of the atrial activation event window of the previous cardiac cycle 121D ( FIG. 11 Branch "NO" of block 110). Processing module 40 may control stimulation module 44 to deliver ventricular pacing pulse V _P 134 to right ventricle 22 , the ventricular pacing pulse timed as ventricular pacing pulse 130 immediately preceding cardiac cycle 121D.

Furthermore, in response to determining that an atrial activation event A _ACT was not detected within a modified atrial event detection window W _AACT beginning at the end of the atrial activation event window of the previous cardiac cycle 121D, the processing module 40 may increment the undersensing counter (114) and determining whether the undersensing counter value is greater than or equal to the undersensing threshold (116). In the example shown in FIG. 12 , processing module 40 determines that the undersensing counter value is greater than or equal to the undersensing threshold in cardiac cycle 121E ("YES" branch from block 116). Accordingly, processing module 40 determines that an undersensing event is detected and switches LPD 10A to the asynchronous ventricular pacing mode. In the example shown in FIG. 12 , in a first cardiac cycle 121F, the LPD 10A is in an asynchronous pacing mode, and the stimulation module 44 delivers ventricular pacing to the heart 24 in the VV interval following the pacing pulse 134 of the previous cardiac cycle 121E. Pulse V _P 135.

As described with respect to FIGS. 9 and 10, in the asynchronous ventricular pacing mode, processing module 40 may determine whether intrinsic depolarization of right ventricle 22 (e.g., V _P 132 ), and in response to determining that no intrinsic depolarization of the right ventricle 22 is detected during the VV interval, the processing module 40 may control the stimulation module 44 to deliver a ventricular pacing pulse V _P 134 to the right ventricle 22 . In the example shown in FIG. 12, the time period between subsequent pacing pulses 132, 134 is shown as the VV interval of one or more previous cardiac cycles plus an offset (e.g., about 30 ms to about 150 ms, such as about 50 ms or about 100ms, although it may vary based on heart rate). In some examples, processing module 40 determines the VV interval based on one or more previous cardiac cycles (eg, cardiac cycles 121A, 121B). For example, the VV interval may be the average interval between ventricular activation events of one or more previous cardiac cycles. The VV interval may be indicative of an average or median heart rate such that the deviation results in a pacing rate that may be lower than the patient's 26 previously detected heart rate.

On the other hand, if processing module 40 determines that intrinsic depolarization of right ventricle 22 is detected during the VV interval, processing module 40 may not control stimulation module 44 to deliver ventricular pacing pulse V _P 134 to right ventricle 22 .

Even in asynchronous pacing mode, LPD 10A can sense atrial activation events intermittently. In some instances, it may be desirable for the LPD 10A to deliver atrioventricular synchronized pacing, where possible, in order to help the heart 26 stay in sync. Accordingly, in some examples described herein, after processing module 40 controls LPD 10A to switch from an atrioventricular synchronous pacing mode to an asynchronous ventricular pacing mode, processing module 40 may periodically determine whether an atrial activation event is detected. In response to determining that atrial activation is detected, processing module 40 may control LPD 10A to revert to the AV synchronized pacing mode. LPD 10A configured in this manner can deliver heart rate responsive pacing when the atrial rate is too slow or consistent atrial undersensing occurs while facilitating AV synchronous pacing over asynchronous pacing.

The techniques described in this disclosure, including those ancillary to graphics IMD 16, programmer 24, or various constituent components, may be implemented at least in part in hardware, software, firmware, or any combination thereof. For example, various aspects of the technology may be implemented in one or more processors, including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuits, and such components The components are embodied in a programmer, such as a physician or patient programmer, stimulator, image processing device, or other device. The term "processor" or "processing circuit" may generally refer to any of the foregoing logic circuits, alone or in combination with other logic circuits, or any other equivalent circuit.

Such hardware, software, firmware may be implemented within the same device or in separate devices to support the various operations and functions described in this disclosure. Furthermore, any of the described units, modules or components may be implemented together or separately as discrete but co-operating logic devices. Depiction of different features as modules or units is intended to emphasize different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functions associated with one or more modules or units may be performed by separate hardware or software components, or integrated within common or separate hardware or software components.

When implemented in software, the functionality attributed to the systems, devices, and techniques described in this disclosure can be embodied as computer-readable media (e.g., RAM, ROM, NVRAM, EEPROM, flash memory, magnetic data storage media, optical data instructions on storage media, etc.). The instructions are executable to support one or more aspects of the functionality described in this disclosure.

Various examples have been described. These and other examples are within the scope of the following claims.

Claims (10)

1. one kind is without lead pacing system, including：

It is described to be configured to sense electric heart signal without lead pacing devices and be configured to control pace-making without lead pacing devices Treat the heart for being delivered to patient；And

Processing module, the processing module is configured to：

Based on the electric heart signal and when it is described without lead pacing devices be in atrium and ventricle synchronous pacing pattern in when, detection first Atrial impulses event,

Determine not detect in the detection window started at the first atrial impulses event based on the electric heart signal Second atrial impulses event, and

The second atrial impulses event is not detected in the detection window based on determination and controlled described without lead Pacemaker impulse is delivered to the ventricle of patient according to asynchronous ventricular pacing mode by equipment of fighting.

2. the system as claimed in claim 1, it is characterised in that the processing module is configured to come at least through following operation Control is described to deliver pacemaker impulse without lead pacing devices according to the asynchronous ventricular pacing mode：

In response to determining not detecting the second atrial impulses event in the detection window, it is incremented by counter；

After the counter is made incrementally, whether the value for determining the counter by the processing module is more than or equal to threshold Value；And

In response to determining that the value of the counter is more than or equal to threshold value, set by processing module control is described without lead pace-making It is standby to deliver pacemaker impulse in asynchronous ventricular pacing mode.

3. the system as any one of claim 1-2, it is characterised in that the threshold value is entered between one, two or three Row selection.

4. the system as any one of claim 1-3, it is characterised in that the electric heart signal includes the first electric heart Signal, wherein, it is described to be configured to the electric heart of the sensing second before first heart signal is sensed without lead pacing devices Signal, and wherein, the processing module is configured to determine the detection window at least through following operation：

Multiple atrial impulses events are detected based on the described second electric heart signal；

Phase between determining between every continuous two atrial impulses events in the multiple atrial impulses event；And

The average length of phase between determining between every continuous two atrial impulses events in the multiple atrial impulses event, its In, duration of the detection window is the average length based on the phase between described.

5. the system as any one of claim 1-4, it is characterised in that the electric heart signal includes the first electric heart Signal, wherein, it is described to be configured to the electric heart of the sensing second before first heart signal is sensed without lead pacing devices Signal, and wherein, the processing module is configured to determine the detection window at least through following operation：

First ventricular sense event is detected based on the described second electric heart signal；

Second ventricular sense event is detected based on the described second electric heart signal, second ventricular sense event is described the Next ventricular sense event after one ventricular sense event；And

It is determined that the phase between first and second described ventricular sense event, wherein the duration of the detection window is to be based on Phase between described between first and second described ventricular sense event.

6. the system as any one of claim 1-5, it is characterised in that the processing module is configured to：

First ventricular sense event is detected based on the electric heart signal sensed；And

Second ventricular sense event is detected based on the electric heart signal sensed, wherein, the processing module is configured to determine The second atrial impulses event is not detected in the detection window to be included at least through determining described first and the The second atrial impulses event is not detected between two ventricular sense events.

7. the system as any one of claim 1-6, it is characterised in that the processing module be configured at least through Operate below control it is described in the atrium and ventricle synchronous pacing pattern pacemaker impulse is delivered to without lead pacing devices it is described Patient：

Detect the 3rd atrial impulses event；And

The predetermined period of time without lead pacing devices after the 3rd atrial impulses event is controlled by pacemaker impulse It is delivered to the ventricle of the patient.

8. the system as any one of claim 1-7, it is characterised in that the detection window is the first detection window, And wherein, the processing module be configured at least through it is following operation come control it is described without lead pacing devices described different Pacemaker impulse is delivered to the patient in step pacing mode：

Detect ventricular sense event；

Determine whether to be that the intrinsic of the ventricle is detected in the second detection window started at the ventricular sense event to go Polarization；And

Intrinsic depolarising in response to not detecting the ventricle in second detection window, is controlled described without lead Pacemaker impulse is delivered to the ventricle by equipment of fighting.

9. the system as any one of claim 1-8, it is characterised in that the asynchronous pacing mode is rate adaptation 's.

10. system as claimed in any one of claims 1-9 wherein, it is characterised in that it is many that the processing module is configured to detection Individual ventricular sense event, based on the phase between the average VV of the multiple ventricular sense event determination, is controlled described without lead pacing devices Pacemaker impulse is delivered to add the speed of skew equal to the phase between the average VV according to the asynchronous ventricular pacing mode.